Method for the control of undesired grasses



United States Mansonron "rim oolsrnononuisinnsmnn GRASSES Burton V. Tpornman, Scotts, Mich., assignor to The Dow conipany, *Midlandf-Mih, n corporation of Behiwai-e jlfiobrawing. ApplicationQctober.13,1954, Serial'No. 462,102 r oom 111'" .4 ret il-4m This-invention relates tto a method for the-control-of undesired grasses and is particularly directed toaa' method.

- rfor the selective control of annual gramineous weeds.

, In recent. years a variety of chemical herbicidesshave been 'developed for the solution --of a I number --of =agricultural. problems. "For example, agents -are being marketed for I the '-control "of broad leaved weeds --in the presence of narrow-leaved-cropssuch as the cereals :and

sugar cane. Also-successful-chemicalcontrolof narrow- Jeavdsweedsin therpresence of certain broad-leaved crops --has---been--reported. -However,-amajomproblem, notspre- -viouslywsolved, is -presented wherenarrow-leaved weeds Jinfest plantings of-desirablenarrowdeavedspeciesaa 'rl hus,

; wild --oa-ts-'area--major pest in the wheat fields of :the

Northern Plains States and crab grass constitutes :a-sprobslem-in lawns and--crops.

-It-is an object -of"-the present invention .to provide a novel method-for thecontrol of undesired annual .grasses. ltisafurther object-to provide a. methodfor theselective control of annualigrass weeds in the presence of desirable rrplant speoies. --Further objects will become apparent from the followingspecificationandwlaims.

According to-therpresent .inventionit :has been Qdiscovered =-that r 4-chloropheny-l -4 -chloroben zenesulfona te 1 when distributed so as-to contact the-seed of-"annual .igrasses posi-tioned: in ttic soil suppressesthe germination andsgrowth-of such-seed. It isamong-the-adyantages..of;

l theuinvention' that thesuppression of mndesired aannual grasses is accomplished without appreciablesiinjury ato established plants or to the seed of many desirable plant species.- sua ifisinglyfiit has beeti foufld' tliat arinual grass weeds such as vviltl.oa tscan be-suppressed in spring and winter wheat with only minimal injury .to the latter.

Irr'carr'ying our-theinveittiomit is essential to iiisttibute a growth-inhibiting amount of the active sulfonate material in the soil in close proximity to the seed of the plants to be controlled. In practice it is usually advantageous to employ a liquid or finely-divided solid carrier to facilitate the uniform distribution of the sulfonate in the soil. In one mode of operation a composition containing 4-chlorophenyl 4'-chlorobenzenesulfonate is sprayed or dusted onto the surface of the soil and thereafter mixed into the upper layers of the soil in any suitable fashion, as for example, with a disc and drag combination. Alternatively, the active sulfonate may be washed into the germination zone by overhead irrigation following application to the soil surface as set forth above. In one preferred method of operation, and particularly in the treatment of stands of desirable vegetation infested with annual grass seed, the sulfonate is applied in the form of an aqueous emulsion using sufficient of the aqueous carrier to accomplish the distribution of the toxicant through the desired cross-section of the soil.

The exact depth of soil to be treated will vary depending upon the type of soil and the particular species of plant to be controlled. For example, the seed of crab grass (Digizaria sanguinalis) rarely germinate if positioned at a depth of more than half an inch in the soil. For the "*2 ,7 control of crab grass,-therefore, the distribution of the sulfonate compound in p a growth inhibiting amount "throughtheupper-one half'to one manor the-soil serves other hand-the; seed of certain other annuabgrasswee'ds inches in certain soils. *For "the control of such-"grasses, th snlfonatetoxicantis distributed throughthe upper 310 formulations "can be' 'employedtor the "distribution at the l-'tzhlorophenyl '4'=clilorobenzenesulfonate toxicant in ac- 'cordance with "thejpresent'invention. Dusts may be-preparedby 'grin'dingto'gether the sulfonate and a finely "divided 'inertrarr'ier such talc,"pyrophyllite; diatomac'equs earth "or clay. Similarly,- the sulfonate" toxicant may be ground together 'with 'both a finely 'divided inert carrier,

' as? set forth abovefand suitable wetting and dispersing agents such as alkyl 'a'ryl sulfonates; "ar'y'l' polyether alco- 'h0lS, ligninsulfona'tes, *long chain-alkyl'sulfate's arid-sulffcina tesand the.likeioptoducewettable powder composi- "tio s adapted" for" 'theprepar'ation'iof' aqueous "dispersions io ffth b ftoxicant; A preferred composition comprises an aqueous dispersion "of a liquid *emulsifiab'le concentrate containing thesulfonate't'oxicant. Such concentrates may be prepared by dissolving-together the sulfonate toxicant and an. oil soluble emulsifyingagentin a solvent such as toluene, xylene,chlorinatedfhydrocarbons or solvent. oils obtaiiied frbm the refining of petroleum.

The amouiit'jdfthesulfonate"toxicant' to be' employed will vary-fde er'iding'npon 's'uclilifacto'rsas'the'type Ofsoil, moisture conditions temperature"and-thevariety 'of'plant to be controlled. In"gene'r'al,jgo'od'results 'are'obtained vsihe'rithe sulfonateisiiisnibutedat a "rate of "from'abont" 5,

ov o'sage iofironi. about "1' 0 to 40 parts :by e an onate;per rriillion'jpartsof so'il. Th foil wing e V fmpl c'srillu's'tr 'ateithe invention'i-but are construd'a 'liitiit'ing"the}same: I

Example 1 21.75 parts by weight of a commercial 4-chlorophenyl 4'-chlorobenzenesulfonate product containing 92 percent by weight ofsaid sulfonate and 8 percent of inert ingredients was dissolved in a mixture of 73.25 parts by weight of xylene and 5 parts of a dimeric alkylated aryl polyether alcohol (Triton X-155) to prepare a liquid emulsifiable concentrate composition. The latter was dispersed in water to prepare an aqueous emulsion spray composition containing 4.6 pounds of the sulfonate per 100 gallons of solution. This spray composition was ap plied with a pressure sprayer to an area of established blue grass lawn in central Michigan in late May, when crab grass (Digitaria sanguinalis) had not yet emerged, although the treated area was known to be heavily infested with crab grass seed. The application was carried out at the rate of 435 gallons of the spray composition per acre to provide a dosage of 20 pounds of 4-chlorophenyl 4'- chlorobenzenesulfonate per acre. Adjacent areas of the lawn were left unsprayed to serve as checks. The weather following the application was warm and moist and crab grass emerged in the untreated areas about 9 days after the treatment. Inspection of the treated and untreated areas about one month after treatment showed 95 perin generalpany of the conventional-types "of herbicidal 85 percent of the checks.

'cent'control of crab grass in the treated area with no observable injury to the established lawn grass. In the check areas crab grass was growing profusely and vigorously.

Example 2 emulsion composition containing 0.213 pound of the sulfonate per 100 gallons. This emulsion composition was I in the untreated check areas had emerged well and made 1 vigorous growth. In the treated areas wheat, barley,

applied as a soil drench at the rate of 0.434 acre-inch of composition per acre of soil to areas of fertile sandy loam previously planted with seed of winter wheat, radish and wild oats. The above procedure resulted in the application of the sulfonate at the rate of pounds per acre distributed through about 3 inches of soil to provide a dosage of about 41 parts by weight of the sulfonate per million parts of soil. Similarly planted areas of soil were maintained untreated to serve as checks. About 3 weeks after the application, it was observed that the seeded species had emerged and were growing vigorously in the untreated check areas. In the treated areas wheat plants were growing in number and vigor substantially equal to that of the checks and radish plants to the extent of about In the treated areas there was essentially no growth of wild oats.

Example 3 25 parts by weight of 4-chlorophenyl 4-chlorobenzenesulfonate and 10 parts of Triton X-155 were dissolved of 20 pounds of sulfonate per acre distributed through about 1.5 inches of soil. This dosage corresponds to about 64 parts by weight of the sulfonate per million parts of soil. Similar areas of soil, planted to the same varieties of seed were left untreated to serve as checks. All areas were maintained under conditions of temperature and soil moisture favorable to the emergence and growth of the seed. On observation about one month after the planting, it was found that all the plant species rye, onions, corn, soybeans, buckwheat, cranberry beans, peas, cotton, radish, cucumbers and flax showed emergence and growth equal to that of the corresponding species in the untreated check areas while foxtail showed growth only to the extent of 10 percent of the cheeks and there wereno living plants of millet, timothy and crabgrass.

I claim:

1. A method for the control of annual grass weeds which comprises distributing 4-chlorophenyl ;4'-chlorobenzenesulfonate in intimate admixture with the soil in close proximity to annual grass seed under ambient conditions normally leading to the germination and growth of such seed, said sulfonate being employed in amount suflicient to suppress the growth of said seed.

2. The method of claim 1 in which the sulfonate is employed in the amount of at least 5 pounds per acreinch of soil.

3. A method for the control of annual grass weeds which comprises contacting the seed of such grasses, while positioned in soil under conditions normally leading to the germination and growth of said seed, with 4- chlorophenyl 4'-chlorobenzenesulfonate in amount sufficient to suppress the growth of said seed.

4. A method for the control of undesired annual grasses in established turf which comprises distributing 4-chlorophenyl 4-chlorobenzenesultonate in the upper layer of the soil in which the turf is growing, said sulfonate being employed at a dosage suflicient to suppress the growth of annual grass seed without adversely afiecting the established turf. I

5. A method according to claim 4 in which the sulfonate is distributed in the form of an aqueous emulsion containing suflicient of the aqueous carrier to accomplish the distribution of the sulfonate toxicant through at least the upper 0.25 inch of the soil.

6. A method for the control of undesired annual grasses in soil seeded to desired crops and infested with seed of said grasses which comprises distributing 4 chlorophenyl 4'-chlorobenzenesulfonate in intimate ad mixture with at least the upper 0.25 inch of the seeded soil, said sulfonate being employed in an amount suflicient to suppress the growth of annual grasses without adversely affecting the germination and growth of the desired crop.

References Cited in the file of this patent UNITED STATES PATENTS 2,678,878 Stewart May 18, 1954 

1. A METHOD FOR THE CONTROL OF ANNUAL GRASS WEEDS WHICH COMPRISES DISTRIBUTING 4-CHLOROPHENYL 4''-CHLOROBENZENESULFONATE IN INTIMATE ADMIXTURE WITH THE SOIL IN CLOSE PROXIMITY TO ANNUAL GRASS SEED UNDER AMBIENT CONDITIONS NORMALLY LEADING TO THE GERMINATION AND GROWTH OF SUCH SEED, SAID SULFONATE BEING EMPLOYED IN AMOUNT SUFFICIENT TO SUPPRESS THE GROWTH OF SAID SEED. 